Previously some parts of the compiler referred to them as "fields",
and most referred to them as "elements". Use the more generic 'elements'
nomenclature because that's what we refer to other things in the compiler
(e.g. the elements of a bracestmt).
At the same time, make the API better by providing "getElement" consistently
and using it, instead of getElements()[i].
NFC.
Swift SVN r26894
We can't just recursively process types without caching. Instead mark a type as
safe before we recurse and reset this assumption if we proved otherwise on the
recursive traversal.
rdar://20132313
Swift SVN r26048
This adds an analysis to the compiler that identifies types that are may store
to memory on destruction.
It adds a compiler known protocol _DestructorSafeContainer that allows the
standard library to identify containers whose destructor's memory effects
depends strictly on the type parameters of the container.
Array<T> : _DestructorSafeContainer {} may not store to memory during
destruction if the bound T is a type that does not store to memory on
destruction.
This is needed to deduce that for example Array<Array<Int>> is does not store to
memory on destruction (e.g during a call to release).
rdar://18940376
Swift SVN r23242
